VITEIFIED BRICK PAVEMENTS FOR COUNTRY ROADS. 27 
slag, and sufficient water to form a quaky mass, and shall be thoroughly mixed 
in a machine mixer of the batch type so constructed and operated that the 
thorough mixing of the materials will be assured. The concrete shall be so 
delivered to its place on the subgrade as not to cause or permit any separation 
of the materials. Wheelbarrows or other devices used for measuring the 
materials shall be of uniform capacity. The concrete shall be deposited in place 
immediately after it is mixed and shall be well compacted as fast as it is 
placed. The top surface shall be smoothed by troweling with shovels or by some 
other means approved by the engineer, and when completed shall not vary 
more than one-half (j) inch from the proper shape and grade, as shown on the 
plans and profiles. The concrete base shall be kept wet by sprinkling with 
water during the first four (4) days after it is laid. No hauling over it or roll- 
ing or tamping of brick upon it will be permitted for seven (7) days after it is 
placed, and during this time it shall be properly protected from injury. Con- 
crete shall not be mixed when the temperature of any of the materials is less 
than thirty-five (35) degrees Fahrenheit. Concrete shall not be used after it has 
begun to show evidence of setting, and no concrete which has once set shall 
be used as material for mixing a new batch. 
Curbs. — Concrete curbs shall be built on the base as shown on the plans. The 
concrete shall be composed of the following materials, by volume: One (1) part 
of cement, one and one-half (1*) parts of sand, three (3) parts of gravel or 
crushed stone, and water. The materials shall be thoroughly mixed in a machine 
mixer of the batch type or by hand. If the mixing is done by hand, it shall be 
done upon a water-tight platform with raised edges, in the following manner: 
The sand and cement shall be thoroughly mixed dry and spread out upon the 
mixing platform, and upon this dry mixture shall be spread the coarse aggregate. 
Water shall then be poured over the aggregate in such an amount that the 
resultant concrete will be of a quaky consistency. The whole mass shall then 
be turned with shovels until all of the materials are thoroughly mixed. The 
concrete for the curb shall be placed upon the base before the concrete of either 
the curb or the base has taken its initial set, and care shall be taken, such as 
roughening the concrete of the base and tamping the concrete of the curb, to 
insure that the curb will be firmly bonded to the base. The concrete shall be 
well tamped and spaded along the forms, so that when they are removed there 
will be no open and porous places on the sides of the curb. The top surface of 
the curb shall be floated or troweled to a smooth finish. The forms for the curb 
shall be smooth, clean, free from warp, and of sufficient strength to resist 
springing out of shape. They shall be well staked and braced, and the top edges 
shall be at the same height and set true to line. To protect the curb from 
drying out too rapidly it shall, within twelve (12) hours after it is placed, be 
covered with gunny cloth, which shall be kept wet for five (5) days. 
Sand cushion. — Upon the base shall be spread a cushion of sand such that it 
will have a uniform depth of two (2) 1 inches when compacted. The base shall be 
thoroughly clean at the time the sand is spread. The cushion shall be care- 
fully shaped to a true cross section of the roadway by means of a template 
having a steel-faced edge, and so fitted as to be readily drawn on the curb. 
After the cushion is so shaped it shall be rolled with a hand roller until the 
sand is well compacted. The depressions formed by rolling shall be filled and 
the surface of the cushion trued up with the template and rolled again. This 
operation of filling depressions, truing up with template, and rolling shall be 
repeated as often as is necessary to secure a well-compacted cushion true to 
1 A sand cushion having a uniform depth of \\ inches is frequently used and may be 
as satisfactory as the 2-inch cushion. 
